The invention is based on a reciprocating piston pump as set forth hereinafter.
German Offenlegungsschrift 22 43 138 discloses a reciprocating piston pump having a housing with two pistons disposed in the housing so as to be displaceable in opposite directions, having an eccentric between the pistons, with transverse bores disposed in the ends of the pistons pointing toward the eccentric, and with an essentially semicircular hoop spring made of spring steel wire, whose ends engage the transverse bores of the piston ends and press these ends of the piston against the eccentric. The hoop spring can be made economically, but it is very difficult to keep the transverse bores aligned essentially parallel to one another, and to keep them aligned in such a way that the ends of the hoop springs can be inserted. This may be made even more difficult because an eccentric chamber located in the housing is open on only one side, for instance. Moreover, the hoop spring ends must be secured against coming out of the transverse bores; this could be done for instance by bending the ends after they have been inserted through the transverse bores. To limit pendulum motions of the hoop spring about the longitudinal axes of the piston, a groove is machined into the housing beginning at the eccentric chamber, and the hoop spring enters this groove. If a reciprocating piston pump of this kind is supposed to be light in weight and its housing is therefore made of aluminum, then it cannot be precluded that aluminum will be worn away from the housing, thereby soiling the reciprocating piston pump and possibly causing disruptions in operation over the course of time.
German Patent Reference DE 41 02 364 A1 discloses a further reciprocating piston pump with a housing that has an eccentric chamber, with pistons disposed facing one another relative to an eccentric, and with annular grooves disposed on the ends of the pistons pointing toward the eccentric, which grooves are engaged by the forklike ends of a hoop spring that is curved around the axis of the eccentric. This reference does not disclose how pendulum motions of the hoop spring about the longitudinal axis of the pistons could be limited or how contact of the hoop spring with the housing could be avoided.